Walk-behind trowelling machines incorporate a rotor that carries a plurality of surface working members or trowelling blades. To provide directional movement of the machine over the surface to be trowelled, the operator manually exerts a force on the handle to tilt the machine and apply downward pressure at specific locations on the periphery of the machine to obtain the desired directional movement.
Riding-type trowelling machines have also been utilized, which incorporate two or more rotors, each of which carries a plurality of trowelling blades. As described in U.S. Pat. Nos. 3,936,212 and 4,046,484, directional movement of the riding-type trowelling machine is achieved by a mechanism, in which each rotor is hinged to the frame and the operator applies selective downward tilting pressure to specific locations on the guard rings that surround each rotor. The pressure is applied by a complicated linkage system actuated by a control stick and foot pedals. Through this system, the rotors can be individually tilted with respect to the frame to cause directional movement of the machine over the surface.
With the directional control system as described in the aforementioned patents, the operator must continually apply pressure to the hand and foot controls to cause directional movement of the machine. The continual application of pressure can be fatiguing to the operator over an extended period of time.